BOUNDARY-ELEMENT ANALYSIS OF FATIGUE-CRACK PROPAGATION IN STIFFENED PANELS

This paper presents the dual boundary element method (DBEM) for the an alysis of crack propagation in aircraft-stiffened panels. DBEM can be used to perform mixed mode analysis in panels with single or multiple cracks, stiffened with riveted, bonded, or integral stringers, The sti ffeners attachment can be modeled as rigid or flexible with plastic or elastic-plastic behavior, Several examples of stiffened panel problem s are presented to demonstrate the accuracy and flexibility of the tec hnique. In one example, the crack growth rates calculated from the str ess intensity factors obtained with the method are compared with exper imental results and shown to be in good agreement, Another example stu dies the influence of cracks at adjacent stiffeners on a crack at a ce ntral stiffener. The central stiffener can be broken or intact and the adjacent cracks can be aligned with the central crack or not. An exam ple to illustrate the application to multiple site damage problems in fuselage lap joints is also presented.